Recently, an alternative multi-delivery policy into imperfect economic production quantity (EPQ) inventory model with partial rework has been proposed, which considers the number of shipments a fixed and given value. This paper, treating the long-run average costs per unit time as a function of the replenishment lot size and the number of shipments , adopts the differential calculus approach to get the optimal solution of and jointly. In numerical examples, it is illustrated that the solution procedure is simple and accurate.